1. Field of the Invention
The present invention generally relates to the technology for polishing works having a circular outer periphery such as substrates of magnetic disks.
2. Related Art Statement
There is known a polishing apparatus which is adapted to polish a plurality of substrates of magnetic disks in a mass producing fashion. One of such apparatus includes a pair of turn tables which are provided in a lower position and an upper position, respectively, so as to oppose each other. The lower turn table, which is provided at the lower position, has a polishing surface on its upper surface while the upper turn table, which is provided at the upper position, has a polishing surface on its lower surface, whereby the polishing surface of the lower turn table and the polishing surface of the upper turn table are disposed in an opposing fashion.
Then, plural sheets of disk-like carriers are provided on the upper surface of the lower turn table. Each of the carriers is provided with at least one aperture, and a work such as a magnetic disk substrate or the like is held within the aperture. The each of the carriers also has a gear formed on its circular periphery so that the gear can be engaged with an internal gear provided at the outer periphery of the lower turn table and a sun gear arranged on a sun gear shaft that is coaxial with a rotary shaft of the lower turn table.
As the sun gear is driven to rotate in one direction and the internal gear also is driven to rotate in a direction opposite to that direction, each of the carriers holding a number of works therein revolves around the sun gear while rotates on its own axis. By the way, either one of the sun gear and the internal gear may be kept stationary to maintain the revolution and rotation at the same time.
The upper turn table is coupled to a lifting and lowering mechanism so that the upper turn table can be lifted to enable an operator to access the carriers on the lower turn table and also can be lowered to bring the upper turn table to contact to the carrier surface. The upper turn table is lowered to contact to the carrier and the upper and lower turn tables are rotated, then the carriers holding works therein will move in a sliding fashion between the upper and lower polishing surfaces while maintaining the above-described revolution and rotation. In this way, both the upper and lower surfaces of the works are polished. A polishing apparatus having the above-described arrangement is disclosed in, for example, Japanese Patent Application Laid-Open Gazette No. 3-149179.
The process for manufacturing substrates of magnetic disks includes many polishing steps, and thus such process requires a lot of time to execute. After cutting a raw substrate that is typically made of aluminum or glass into a disk-shape, the process goes into many steps of polishing. For example, the process includes a grinding step for grinding the surface of a work or substrate by means of a grinder, a lapping step for improving the finish of the work and a polishing step for providing the work with a high precision surface profile. For lapping and polishing, a polishing tool such as a polishing pad or a buff is used in a polishing apparatus of the above described type.
The nature of the process tells us that several polishing steps are carried out by commonly utilizing substantially the same polishing apparatus. In other words, the aforesaid polishing steps, or the grinding, lapping and polishing processes, are carried out by an apparatus having substantially the same configuration. Therefore, it is requested to provide a method and an apparatus which enable a number of works to be polished in an efficient mass production manner on the floor of a limited area on which the apparatus will be provided.
It is an object of the present invention to provide a method and an apparatus that can increase the number of works to be polished simultaneously.
It is another object of the present invention to provide a method and an apparatus that can improve productivity in polishing works or the like.
It is still another object of the present invention in which a working area on which the aforesaid apparatus will be provided can be utilized efficiently.